• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.393-396
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• 2002

Submerged gas-injected system can be applied to various industrial field such as metallurgical and chemical processes, So this study aims at presenting the relevant relationship between gas phase and liquid phase in a gas-injected bath. In a cylinderical bath, local gas volume fraction and bubble frequency were measured by electroconductivity probe and oscilloscope. The temperature of each phase was measured using thermocouple and data acquisition system. In vertical gas injection system, gas-liquid two phase plume was formed, being symmetry to the axial direction of injection nozzle and in a shape of con. Lacal gas-liquid flow becomes irregular around the injection nozzle due to kinetic energy of gas and the flow variables show radical change at the vicinity of gas(air) injection nozzle As most of the kinetic energy of gas was transferred to liquid in this region, liquid started to circulate. In this reason, this region was defined as 'developing flow region' The Bubble was taking a form of churn flow at the vicinity of nozzle. Sometimes smaller bubbles formed by the collapse of bubbles were observed. The gas injected into liquid bath lost its kinetic energy and then was governed by the effect of buoyancy. In this region the bubbles which lost their kinetic energy move upward with relatively uniform velocity and separate. Near the gas nozzle, gas concentration was the highest. But it started to decrease as the axial distance increased, showing a Gaussian distribution.

• 한국안전학회지
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• 제18권1호
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• pp.14-18
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• 2003

The structural development of air-water bubble plumes has been measured under different condition on air flow rate in a cylindrical bath. The time-averaged structure of plumes has been measured with an oscilloscope and an electro-conductivity probe. The temperature of bubbles was also obtained by a thermal-infrared camera. Gas volume fraction and bubble frequency were high since bubbles concentrated on the nozzle. In general, their axial and radial values tended to decrease with increasing distance. Bubble temperature reached water temperature within a short time. The present study showed that thermal equilibrium between bubbles and water was completed before bubbles flow became stable.

• 드라이브 ㆍ 컨트롤
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• 제16권1호
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• pp.1-6
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• 2019

The use of micro bubbles in industrial fields has been increasing in the recent years., particularly micro-bubble sterilization and water purification effects. Various methods have been developed for the generation of micro-bubbles. Depending on the method of generating bubbles, the micro-bubbles can be roughly classified into saturation molding, cavitation and rotation flow types. The objective of this study was to use ventilated tube type as a method of generating micro-bubbles in order to purify large amount of water quality such as lakes and reservoirs. This method shows a difference in efficiency in which micro-bubbles are generated depending on the contact ratio of gas to liquid. The study also investigated the optimal gas liquid contact ratio by applying various orifice methods and investigated the optimum condition of micro-bubble generation by gas Based on this, a technology to develop a micro-bubble generator with a venturi type nozzle shape that has a high water purification effect was developed.

• 한국주조공학회지
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• 제6권4호
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• pp.269-276
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• 1986

The effects of Se, $CaCO_3$ and CaO addition on the first stage graphization of malleable iron were evaluated. The results obtained in this work were as follows. 1. Many gas bubbles were found in the white cast iron under Se, $CaCO_3$ addition. 2. Nodular graphite were formed by annealing of the white cast iron with remained gas bubbles. 3. When specimens were annealed, bubbles provided the nucleation sites that were needed in graphite precipitation, so the nucleation rate of graphite was increased. 4. The remained gas bubbles and defects were more effective for the graphitization than metallic compounds.

• 대한토목학회논문집
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• 제9권4호
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• pp.135-143
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• 1989

깊이 32m인 심층포기장치에서 기포(氣泡)의 형태(形態)와 거동(擧動)에 관하여 실험연구(實驗硏究)를 실시하였다. 연구(硏究) 결과(結果)에 의하면, 심층포기장치의 하향관(下向管)에 설치된 0.06cm의 단일(單一) 오리피스경(經)에서 발생되는 기포(氣泡)의 구체적(球體積) 상당경(相當經)(Dv)은 0.422-0.722cm이고 기포(氣泡)의 형상(形狀)은 타원체(橢圓體)이었다. 기포(氣泡) 체류량(滯留量) 기(氣)-액(液) 접촉면적(接觸面積)은 심층포기장치의 수심(水深) 증가(增加)할수록 감소(減少)하였으며, 기포(氣泡)의 하강속도(下降速度)는 액체(液體)의 순환(循環)유속보다 작고, 기포(氣泡)의 상승속도(上昇速度)는 액체(液體)의 순환(循環)유속보다 약간 크게 나타났다. 심층포기장치내의 기포분포(氣泡分布)는 거의 대수정정규분포(代數定定規分布)를 나타내고 있으며, 또한 기포(氣泡)의 갯수는 수심(水深)이 증가(增加)할수록 감소(減少)하며, 하향관(下向管)이 상향관(上向管)에 비하여 많았다.

• Nuclear Engineering and Technology
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• 제26권3호
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• pp.374-380
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• 1994

결정립계에 존재하는 핵분열기체의 기포가 소결체의 외부와 연결되는 정도를 모사할 수 있는 방법을 개발하였다. $UO_2$ 결정립의 형상을 TKD로 취급할 때, 결정립 Corner에서 자유 공간과 연결되는 핵분열 기체의 기포 비율을 결정립 Corner에 형성된 기포 반경의 함수로서 몬테 카를로 방법을 이용하여 계산하였다. 2차원적인 분석에도 불구하고, 본 방법은 모든 기포가 자유 공간과 완전히 연결된 순간에서 예측된 핵연료 팽윤과 측정된 핵연료 팽윤이 비교적 잘 일치함을 보였다. 그러나 핵분열기체 기포가 외부와 상호 연결된 정도를 좀 더 사실적으로 모사하려면 결정립 Corner의 기포를 3차원적으로 취급해야 한다.

• Korean Chemical Engineering Research
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• 제59권3호
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• pp.379-392
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• 2021

본 연구에서는 초음파 캐비태이션 버블와 가스 버블를 이용한 파클리탁셀의 개선된 아세톤-물 분별침전 공정을 개발하였다. 전통적 방법에 비해 침전에 소요되는 시간이 20~25배 단축되었다. 또한 파클리탁셀의 침전물 크기는 3.5~5.5배 감소하였으며 파클리탁셀의 확산 계수는 3.5~6.7배 증가하였다. 초음파 캐비태이션 버블을 이용한 침전의 경우 초음파 파워는 증가할수록, 침전 온도는 감소할수록 침전 속도 상수는 증가하였다. 가스 버블을 이용한 침전의 경우 가스 유량은 증가할수록, 침전 온도는 감소할수록 침전 속도 상수는 증가하였다. 열역학적 해석을 통해 개선된 분별침전은 비자발적 발열 공정이었다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.85-88
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• 2002

In order to visually analyze the flow characteristics, gas was injected into the liquid bath through nozzle installed at the center of bottom of the bath. When gas was injected into the liquid bath, several flow patterns were observed bubble-liquid plumb, the spout flow that occurred at the free surface, liquid circulation flow by bubble's behavior, etc. Various bubbles, from small bubbles to Taylor bubbles, consisted of the bubble-liquid plumb. In the pure liquid region, the large and small several vortices were formed and irregularly circulated. These irregular repetition and circulation play a important role of mixing in the bath. The vortices were developed in the upper and the side wall regions and the movement of flow in the low region was very small. It is known as 'dead zone'.

• Korean Chemical Engineering Research
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• 제50권2호
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• pp.304-309
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• 2012

동력학적 기체유출방법(dynamic gas disengagement method)과 이중전기저항 탐침방법(dual electrical resistivity probe method)을 동시에 사용하여 기포탑에서 큰 기포와 작은 기포의 크기를 구별하였다. 기포탑의 일정한 운전조건에서 기포탑 내부에 체류하는 큰 기포와 작은 기포의 체류량은, 기포탑에 유입되는 기체의 유입을 차단한 후 시간의 흐름에 따른 기포탑 내부의 압력강하 변화를 측정하여 동력학적 기체유출방법에 의해 측정하였다. 기포의 크기와 빈도수는 동력학적 기체유출방법에 의해 큰 기포와 작은 기포의 체류량을 측정하는 동일한 운전조건에서 측정하였으며 이들 자료들로부터 기포의 크기에 따른 기포의 체류량을 결정하였다. 기포탑에서 큰 기포와 작은 기포의 크기결정은 동력학적 기체유출방법에 의해 얻은 큰 기포와 작은 기포의 체류량과 이중전기저항 탐침법에 의해 구한 크기의 범위를 아는 기포들의 체류량을 비교하여 결정하였다. 여과된 압축 공기와 물을 기체상과 연속액상을 사용하였으며, 기포탑의 직경은 0.102 m이고 높이는 1.5 m이었다. 기포탑에서 큰 기포와 작은 기포의 경계 크기는 4.0~5.0 mm 이었는데, 기체의 유속이 낮은 범위에서는 큰 기포와 작은 기포의 경계 크기가 5.0 mm 정도이었으나 기체의 유속이 상대적으로 큰 범위에서는 큰 기포와 작은 기포의 경계 크기가 4.0 mm 정도가 되었다.

• 한국주조공학회지
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• 제9권6호
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• pp.474-482
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• 1989

The aim of this research is to investigate the effects of gas bubbles on the formation of spheroidal graphite in cast iron, Fe-Si-8%Mg alloy, mischmetal hydride($MmH_2$) and $CaCO_3$, which discharge various amounts of Mg, $H_2$ and $Co_2$, gases, were added to Fe-3.9% C-2.0%Si melt and the melt was innoculated with 0.3wt% of 75%Fe-Si. The spheroidal graphites and/or compacted vermicular graphites were produced with more than 0.625cc/g of Mg gas or more than 0.3125cc/g of $H_2$ gas while $CO_2$ gas did not contribute to graphite spheroidization. Nodule counts increased with the amount of Fe-Si-Mg added ; but they decreased with the amount of $MmH_2$ added because the number of effective gas bubbles decrease with the increase in Mm residual. The bull's eye structure was revealed with 0.625cc/g, 1.25cc/g of Mg and 0.3125cc/g of $H_2$ ; the ledeburite structure was revealed with more than 0.625cc/g of $H_2$.